"""Small formatting and parsing helpers."""

from __future__ import annotations

import re
from datetime import datetime
from typing import Any

def slugify(value: str) -> str:
    slug = re.sub(r"[^a-z0-9]+", "-", value.lower()).strip("-")
    return slug or "untitled"


def normalise_tags(value: Any) -> list[str]:
    if isinstance(value, str):
        raw = re.split(r"[,:\s]+", value)
    elif isinstance(value, list):
        raw = [str(item) for item in value]
    else:
        raw = []
    tags = []
    for tag in raw:
        if not tag.strip():
            continue
        clean = slugify(tag)
        if clean and clean not in tags:
            tags.append(clean)
    return tags


def org_date(dt: datetime) -> str:
    return dt.strftime("<%Y-%m-%d %a %H:%M>")


def parse_org_datetime(value: str | None) -> datetime | None:
    if not value:
        return None
    match = re.search(r"<(\d{4})-(\d{2})-(\d{2})(?:\s+\w+)?(?:\s+(\d{2}):(\d{2}))?>", value)
    if not match:
        return None
    year, month, day, hour, minute = match.groups()
    return datetime(
        int(year),
        int(month),
        int(day),
        int(hour or 12),
        int(minute or 0),
    )


def html_escape(value: str) -> str:
    return (
        value.replace("&", "&amp;")
        .replace("<", "&lt;")
        .replace(">", "&gt;")
        .replace('"', "&quot;")
    )